Duncan
You are, of course, quite right on the roles and the immediate needs.
However, in the same way that any capability involved in 'the war in Afg' has been "immune" from the SDSR (at least from the Army perspective) once QEII is floating on the water (and with F35 perhaps late) there will be a clamour to put something (anything) on it to fend off the 'white elephant' tag (and perhaps save it (or the PoW) from the 'Sales and Wants' ad when the second carrier is launched). And actual capability requirement will play little in the decision process when it comes to saving face (or gaining the political high ground seeing as if DC/NC continue as they are going we could have Ed in No 10 by the time the QE II launches ....).